Electroresponsive device



May 27, 1930. A. COHN 1,760,542

ELECTRORESPONS IVE DEVICE Filed Dec. 4, 1928 2 L, Inventor:

- Alfred C'Ohfi,

His Attorney- Patented May 27, 1930 UNITED STATES P TENT .XOFFICE ALFRED COI-IN, 0F BERLIN, GERMANY, ASSIGNOR T0 GENERAL ELEGTRIGOOMPANY, A

CORPORATION OF NEW YORK ELEGTRORESPONSIVE DEVICE I Application filed December 4, 1928, Serial No. 323,720, and in Germany January 10, 1928.

This invention relates to electroresponsive devices and more particularly to automatic circuit interrupters of the high speed type provided with a direct current holding electromagnet having a tripping winding associated therewith for controlling the path of the holding flux to eifect operation of the interrupter under predetermined circuit conditions.

The principal object of the present invention is to provide improved means for controlling the inductive action between the holding electromagnet and the tripping winding of a circuit interrupter of the above type.

It has been proposed heretofore to reduce the time of response of a high speed circuit interrupter of the above character by utilizing the inductive effect of a rapid increase in' a the current in the circuit controlled by the interrupter. For example, it has been proposed to provide an inductive shunt for the tripping wii'idings in order to'effect the operation of the interrupter with a rapid increase in current to a value which is below the value required for releasing the switch with. a constant current.

In accordance with the present invention, a further reduction in the value of a rapidly increasing current required for operating the interrupter may be obtained by inducing clectromotive forces in the circuit of the holding winding tending to weaken the holding current and thereby cause the interrupter to operate at an even'lower'value of rapidly increasing current. For this purpose, according to the present invention, the interrupter is provided with additional coils which may be linked with the magnetic structure of either the inductive shunt or of the'magnetic arc blowout with which the interrupter ordinarily is provided and are connected electrically or inductively with the holding coil.

Furthermore the additional inductive coils are of particular advantage where the quick acting circuit interrupter is employed to provide reverse current protection. For example, such interrupters may be used in rectifier'installations as reverse current, quick acting, out out switches, for cutting out back igniting rectifiers. In such installations, it

the switch are inductively influenced by'the rapid changes in the forward current. Thus the current which is supplied from the sound rectifiers to the particular rectifier develop-c ing back ignition, at first suddenly increases and then is cut ofi by the operation of the quick acting out out switch associated with the defective rectifier. These rapid variations in the forward current which traverses the tripping winding of the cut out switches associated with the sound rectifiers, inductively aifects such a decrease of the holding current in the-main holding coils of these switches that under certain conditions the switch may be released. 7

In accordance with the present invention the above defectsmay be overcome by inducing an electromotive force in the holding coil circuit of the reverse current protecting cut outs in such a way as to prevent the release of the cut outs associated with the sound rectifiers under the c'onditions outlined above. In the accompanying drawing, Fig. 1 shows diagrammatically a quick acting circuit interrupter embodying the inductive connection /arrangement for the holding windings of the present invention and'Figs. 2 and 3 are oscillographic representations of the rapid changes in current to which the tripping and holding windings of the circuit interrupter may e subjected respective- .ly during back ignition conditions in a rectifier protective installation.

In Fig. 1 the holding electromagnet 1 of the quick acting circuit interrupter is excited by the holding winding 3 which is normally excited with direct current from a suitable source indicated as the battery 20 a 6 tractive relation with the poles of the hold- Q ing electromagnet. A magnetic yoke 4 is disposed between the poles of the holding electromagnet and carries the tripping winding 5. The movable circuit controlling contact arm 6 is normally biased to the circuit opening position by the spring7. An inductive shunt 14 is shown connected in multiple with the tripping winding 5 and is provided with the iron core 15 so as to impart a strong selfinductance thereto. L

In accordance with the usual practice, the

circuit interrupter is provided with a magnetic arc blowout arrangement consisting of'the two arcing horns 10 and 11 and the magnetic blowout coil 12 which is wound around the blowout flux distributing core 13'. The arcing horn 10 is electrically connected with the stationary contact 9 and the arcing horn 11 is electrically connected with movable contact arm 6, so as to divert the are formed upon separation of the contact arm 6 from the stationary contact 9 to the arcing horns.

With the switch closed as shown in Fig. 1, the current in the circuit controlled by the circuit interrupter passes from line L in the direction of the arrow through the movable contact arm 6, the stationary contact 9,

the blowout coil 12, and then divides between the main tripping winding 5 and the inductive shunt 14 and finally leavesthe interrupter by line L The connection arrangement of the tripping winding 5 is such that upon the occurrence of an excessive current in the circuit controlled by the interrupter in a predetermined direction, the flux of the holding electromagnet is diverted from its normal path through the armature 2 into the path through the magnetic yoke 4 thereby permitting the spring to quickly operate the contact arm 6 to the circuit interrupting position. I y

In accordance with the present invention, additional coils 16 or 19 are arranged either on the iron core 15 of the inductive shunt 14 or on the iron core I13 of the magnetic blowout and electrically connected in the holding coil circuit so that they act inductively thereon. Thus as shown in the drawing, the additional coil 19 is wound on the magnetic blowout core and electrically connected in series circuit with the holding coil 3 of the circuit interrupter. In addition, if

desired, the switch 21 may be operated to connect the coil 16 wound upon the magnetic frame of. the inductive shunt ll, also in series circuit with the holding coil 3. I

By means of these'additional coils on the separate magnetic members of the blowout and inductive shunt, various inductive effects upon the holding electro-magnet can be obtained in accordance with the manner in which the coils are adjusted and connected in the circuit.

For example, ifthe additional coils 19 and 16 are connected in series with the hold.- ing electromagnet so that the inductive action produced by an increasing current in the inductii e shunt and the blowout upon the additional coils tends to decrease the value of current in the holding electromagnet, the circuit interrupter is enabled to be released at a lower value of rapidly increasing current than without the additional coils in-the circuit. In this way, the time required for opening the interrupter contacts upon a sudden abnormal risein current is materially shortened by the inductive efi'ect of the additional coils.

Moreover, with the additional coil arranged on the iron core of the magnetic blowout a more effective blowout action is obtained. This is due to the fact that during the opening of the circuit interrupter, the holding electromagnet releases its armature and the resulting sudden change of the flux in the holding electromagnet induces a current in the holding winding 3 which increases the current in the holding coil circuit above its normal value. This current then decreases to the normal value dependent upon the time constant of the holding coil circuit.

The magnetic field produced by the induced current in the holding coil circuit through the agency of the additional coils associated with the arc blowout magnet is in the same direction as the blowout field produced by the winding 12 in the main circuit and therefore renders the blowout action more effective. In this way, the auxiliary coil arrangement on the magnetic blowout tends to reduce/the time of operation of the circuit interrupter by shortening the duration of the arc, in addition to accelerating the release of the holding armature by the inductive action on the holding electromagnet in the manner previouslydescribed.

Furthermore the additional coils are particularly advantageous where the quick acting circuit interrupter is used as a reverse current cut out in a rectifier installation as previously indicated. In such installations, a quick acting circuit interrupter is provided for protecting each rectifier and arranged so as to release in case of back ignition in the rectifier which would cause a reverse current to pass through the interrupter. Thus the tripping winding is so associated with the holding electromagnet as to efi'ect the release of the circuit interrupter upon excessive reverse current but not upon current in the normal direction.

However, as previously pointed out it often happens that the quick acting circuit interrupter of a sound rectifier will release when the current supplied from the sound rectifier to a rectifier developing a back ignition concut out associated with the unsound rectifier.

Lil

With this rapid variation in the current in the circuit controlled by the high speed re verse current cut out of the sound rectifier, the curve 2 in Fig, 3 represents the variations of the current in the holding coil circuit thatmight be obtained without use of the auxiliary coils in accordance with the present invention, In this case, it will be observed that the holding coil current increases from the normal value c to a maximum value d cor responding to the maximum of the main current 6. The holding coil current then decreases to a minimum value 6 as the forward current in the circuit through the tripping winding correspondingly decreases. lit may readily occur that the minimum value c of the holding current may reduce the holding force of the holding electromagnet to such an extent that the reverse current cut out is released, even though the current always is in the forward direction.

However, in accordance with present invention, the above defects readily can be overcome by connecting the auxiliary windings associated with the magnetic blowout or with the inductive shunt 14 so as to induce an electrornotive force in the holding coil circuit tending to prevent the decrease of the current to the minimum value c in the manner illustrated by curve 2 in Fig. 3. Thus with the auxiliary winding connected to provide an induced electromotive force in opposition to that induced in the holding electromagnet due to its inductive relation with the tripping winding, the reduction of the holding coil current to the minimum value 6 may be effectively prevented. As a result the undesired release of the quick acting reverse current cut out of the sound rectifiers may beavoided under the conditions outlined above.

\Vhat has been said with relation to reverse cu rent circuit interrupters subjected to a quick variation in forward current is also applicable to a forward current circuit interrupter subjected to a quick variation in reverse current.

If desired, the additional coils on the magnetic blowout and on the inductive shunt can be provided with suitable taps so that any electromagnet with desired portion of the; coils may be inserted in the holding circuit. In thls way, the 1nductive action of the additional coils on the holding coil circuit may be regulated at will. Furthermore, in place of connectlng the additional coils directly in series with the holding electromagnet, they may be inductively coupled therewith as for example by means of a coupling transformer.

What I claim as new and desire to-secure by Letters Patent of the United States is:

1. In combination, an electroresponsive device having a normally excited holding eleotromagnet, a tripping winding disposed between the poles of the holding electromagnet for controlling the path of the flux of the holding electromagnet to eiiect operation of the device, and separate means inductively interconnecting the holding electromagnet with said tripping winding to control the inductive efl'ect of-the tripping winding on the holding electromagnet upon predetermined rapid variations of current in the tripping winding.

2. In combination, anelectroresponsive device having a movable member biased to one position, a holding electromagnet for maintaining the member in another position, a

tripping winding disposed between the poles, of the holding electromagnet for controlling the path of the holdingflux of said holding electromagnet to permit the movable member to operate in accordance with its bias, an additional winding connected to be energized responsively to the current in the tripping winding, and separate magnetic means inductively lnterconnecting the holding electromagnet with said additional winding to induce an electromotive force in the holding electromagnet upon predetermined variations in the-current of the tripping winding.

3. In combination, a circuit interrupter having a movable switch member biased to the circuit opening position, a magnetic member connected therewith, a normally energized holdingclectromagnet in cooperating relation with said magnetic member for holding the switch member in the circuit closing position, a tripping winding disposed between the poles of the holding electromagnet and energized in accordance with the current in the switch member for shifting the flux of the holding electromagnet from said magnetic member to permit operation of the movable switch member to the circuit interrupting position in accordance with its bias. an additional winding connectedto be energized responsively to the current in the switch member, and separate magnetic means inductively interconnecting the said holding said additional winding to induce an electromotive force in the holding electromagnet during predetermined variations in the current in the switch member.

4. A circuit interrupter provided with an 4 p i 1,700,54a 7 are blowout winding connected to be energized in accordance with the current in the circuit interrupter, and a controlling electromagnet having a tripping winding and a normally excited holding Winding, thesaid holding winding being inductively interconnected with both thetripping winding and the arc blowout winding.

5. In combination, a circuit interrupter. having a movable switch member biased to the circuit opening position, a magnetic mem-- ,ber connected therewith, a normally energized holding electromagnet in cooperating relation with said magnetic member for holding the switch member in the circuit closing position, a tripping winding disposed between the poles of the holding electromagnet and energized in accordance with the current in t e circuit interrupter for shifting the flux of the holding electromagnet from said magnetic member to permit operation interrupter, and an auxiliary winding inductively related to said blowout winding and connected in series circuit with said holding electromagnet'to setup an electromotive force in the holding electromagnet tending to increase the current therein upon a predetermined decrease in the 'current in the circuit controlled by the circuit interrupter in the other direction.

In witness whereof, I have hereunto set 75 my hand this 14th day of November, 1928.

ALFRED OOHN.

of the movable switch member to the circuit interrupting position in accordance with its bias, a magnetic arc blowout winding energized in accordance with the current in the circuit interrupter, and an auxiliary winding inductively related to said blowout winding and connected in series circuit with said holding electromagnet to set up an electromotive' force in the holding electromagnet upon predetermined variations in the current in the interrupter and to strengthen the blowout action upon release of said magnetic member.

6. In combination, a circuit interrupter having a normally excited holding electromagnet, a tripping winding energized in accordance with the current in the interrupter for controlling the path of the flux of the holding electromagnet to cited; operation of the circuit interrupter in response to a predetermined increase of current in one direc tion, and means inductively connecting the holding electromagnet with the tripping winding of the interrupter to prevent operation thereof upon a predetermined decrease in current in the other-direction.

7. In combination, a circuit interrupter having a movable switch member biased to the circuit opening position, a magnetic member connected therewith, a normally ener- 

